Preston climate

Preston Frost Dates and Growing Season

NOAA 1991-2020 normals for Maquoketa, 20.9 km from Preston, elevation 668 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Maquoketa. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around April 25 and the first fall freeze around October 14, a growing season of about 171 days.

Median at 36°F
last May 5, first October 3
Median at 32°F
last April 25, first October 14
Median at 28°F
last April 14, first October 24

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 18May 14May 10May 7May 5May 2Apr 29Apr 25Apr 20
32°FMay 9May 5May 2Apr 29Apr 25Apr 22Apr 18Apr 15Apr 11
28°FMay 1Apr 25Apr 21Apr 17Apr 14Apr 11Apr 8Apr 5Apr 2
24°FApr 20Apr 14Apr 10Apr 7Apr 5Apr 3Mar 31Mar 26Mar 18
20°FApr 7Apr 3Mar 31Mar 28Mar 24Mar 20Mar 15Mar 11Mar 7
16°FMar 31Mar 25Mar 21Mar 18Mar 14Mar 11Mar 8Mar 4Mar 1

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 20Sep 25Sep 28Oct 1Oct 3Oct 5Oct 8Oct 11Oct 16
32°FSep 30Oct 5Oct 9Oct 12Oct 14Oct 16Oct 19Oct 22Oct 26
28°FOct 10Oct 15Oct 19Oct 22Oct 24Oct 26Oct 29Oct 31Nov 4
24°FOct 21Oct 26Oct 29Oct 31Nov 2Nov 4Nov 7Nov 11Nov 16
20°FNov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 20Nov 23Nov 28
16°FNov 6Nov 11Nov 15Nov 19Nov 23Nov 26Nov 29Dec 1Dec 7

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F169164159155151148143139132
32°F189182178174171167163158151
28°F209203198195191187183178171
24°F233225220215211207203199193
20°F256249243238233229224218211
16°F274266261256252247242237231

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
6,943
Cooling degree days, base 65°F
737
Growing degree days, base 40°F
4,963
Growing degree days, base 45°F
3,871
Growing degree days, base 50°F
2,902
Growing degree days, base 55°F
2,052
Growing degree days, base 60°F
1,329

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42400
February1,17201
March917018
April520485
May21251320
June31169588
July7241699
August14188639
September13076402
October4519132
November834017
December1,23201

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 20.9 km from Preston. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00135131 (Maquoketa). Public domain.